Diaphragm for pumps



1953 H. c. PORTER DIAPHRAGM FOR PUMPS 2 Sheets-Sheet Filed April 23, 1948 INVENTOR flan/4rd C. l o/fer BY2 ATTORNEY Nov. 10, 1953 H. c. PORTER 2,658,526

DIAPHRAGM FOR PUMPS Filed April 23, 1948 2 Sheets-Sheet 2 m 1 .5. T: .5. T1 1 5/ m JUL/D 0R FOAM RUBBf R FOAM RUBBER TxlzlEl. T1311.

FOAM RUBBIE'R FOAM RUBBER INVENTOR ATTO R N EY Patented Nov. 10, 1953 UNITED STATES PATENT OFFICE DIAPHRAGM FOR PUMPS Howard 0. Porter, Fairfield, Ill., assignor to Chefford Master Manufacturing Co. Inc., a corporation of Illinois 4 Claims.

This invention relates to flexible cliaphragms subject to reciprocation of one part of the diaphragm with respect to the other, in combination with pumps both for liquids and gases, especially fuel and vacuum pumps of internal combustion engines.

A filler or padding member is mounted between the upper and lower sets of plies or portions of the diaphragm in the free region between their outer edge where they are gripped or clamped by the pump casing, and their central part where they are gripped by or clamped to the reciprocating mechanism of the pump. The filler bulges out the sets of plies in said free region. It is preferably readily compressible but resilient, maintaining the bulge in the plies for all positions of the diaphragm in its reciprocation. As will be explained, this eliminates the development of slack in the diaphragm as it passes from the maximum to the minimum amplitude of its stroke. The inelastic diaphragms of the prior art must develop considerable slack as they reciprocate in order to be operative. As a consequence of the elimination or reduction of slack with my diaphragm, as will be more readily understood later on, its pumping efficiency is better than the diaphragms of the prior art, especially for the strokes of smaller amplitude. The reduction of slack substantially eliminates surges of increased pressure in the pump discharge, especially when operating at high speed. Further, a standard size diaphragm will inherently compensate for the variations occurring in pumps produced on a quantity basis.

With my construction, the flexing of the plies and their slippage over each other are kept small, resulting in longer wear. Lower temperatures, Which stiffen the plies, produce less lossof pumping efficiency in my diaphragmthan in previous diaphragms because of the reduced flexing.

Other objects and advantages Will become apparent upon further study of the description and drawing in which:

Fig, 1' is a vertical section through a fuel pump embodying the padded diaphragm.

Fig. 2 is a sectional plan taken along the line 2-2 of Fig. 1 with certain of the parts broken away.

Fig. 3 is a perspective view of the diaphragm shown by itself, with the plies, however, shown as if they were gripped at their outer edge and at their central part as in the pump.

Fig.4 is a section to an enlarged scale of the diaphragm shown in the neutral or mid-position of its stroke, only portions of immediately adjacent parts of the pump being shown.

Fig. 5 is a partial section of the diaphragm taken similarly to Fig. 4 but showing the diaphragm at the top or suction end of its stroke.

Fig. 6 is a partial section of the diaphragm taken similarly to Fig. 4 but showing the diaphragm at the bottom or compression end of its stroke.

Fig. 7 is a partial section of the left hand portion of the diaphragm to a larger scale than Fig. 4, the diaphragm being shown by itself and in its mid-position as in Fig. 4.

Fig. 8 is a partial section of a modified form of padding member or filler for the diaphragm shown by itself.

Fig. 9 is a partial section of a second modified form of padding member or filler shown by itself.

Fig. 10 is a partial section of a third modified form of padding member or filler shown by itself.

Fig. 11 is a partial section of a fourth modified form of padding member or filler shown by itself, the padding member in this instance being provided with a web or flange, and

Fig. 12 is a partial section of a diaphragm, shown by itself, whose plies are held apart by a liquid or powder filler.

For the purpose of illustrating the construction and functioning of the diaphragm and the padding member, they are shown as parts of a fuel pump, such as is used to pump fuel to the carburetor of an internal combustion engine. It is to be understood, however, that they are useful in many other situations where a reciprocating diaphragm can be employed in conjunction with gases or liquids.

The flexible diaphragm I3 is clamped at its edge between upper casing member H and lower casing member l2, said members being fastened together by screws I l. Diaphragm I3 is fastened at its center to stem IS, the latter passing through an opening 54, Fig. 3, in the center of the diaphragm and through the center of dished metal plates 16 and I1. Mounted on stem [5 below lower plate It is a gasket 19 and a washer l8. Upper plate I! is set on stem it between shoulder 2| formed on the stem and diaphragm l 3. When rivet head 20 is hammered or pressed toward shoulder 25, diaphragm I3 is tightly clamped or gripped between plates [6 and ill which can be considered as part of the reciprocating mechanism of the pump. Lever 22, which is pivoted at 23, has its inner end loosely engaging stem 15 under the latters head 26. Stem i5 is slidably mounted in oil seal 2i. The outer end of lever 22 rides on cam 24 which is mounted on the cam shaft 40 of the engine, not shown. A compression spring 25 is provided between a lug 'll on lever 22 and a lug 42 on upper casing member l Spring 25 causes the outer end of lever 22 to follow the periphery of cam 24. When said cam forces down the outer end of lever 22, its inner end raises stem :5. When the inner end of lever 22 is moved down, it merely slides over stem 15. The return or downward stroke of stem i5 is offected by compression spring 29, the lower end of which engages upper metal plate ll, while its upper end engages oil seal 2i. Mounted on the bottom of lower casing member l2, is glass filter 1 bowl 43 held thereon by the usual bail id and screw 45. Filter screen 33 is mounted between bowl 43 and member 52, the latter being provided with an inlet passage 3|, for leading the fuel through an opening in screen 33 into bowl 23. Member i2 is provided with a port B l in which is located an outlet check valve 35 through which the fuel leaves bowl t3 after having passed through screen 33. The fuel passing valve 35 enters pump chamber 38 from whence it is led to outlet check valve 33. The fuel is discharged from the pump through outlet passage 37 after having passed through check valve 383.

When stem i5 is raised by the clockwise rotation of lever 22, diaphragm is is pulled upward for its suction stroke drawing fuel past valve 35 into chamber 36. The compression stroke or discharge stroke of the diaphragm is effected by spring 29 pushing it down, thereby causing the discharge of fuel from chamber 36 past valve 38. As is well known in the art, when the carburetor, not shown, which receives the discharge from the pump, is filled to a predetermined level, a valve is closed in it which results in resistance to the reception of further fuel from outlet 37 of the pump. Spring 29 in giving diaphragm i3 its compression stroke must act against this resistance. The amplitude of the compression stroke and consequently of the suction stroke is lessened in accordance with this resistance. In other words, when the amount of fuel required by the engine is lessened, the amplitude of the reciprocation of the diaphragm is lessened.

In the particular embodiment illustrated, the diaphragm comprises two upper plies ie and two lower plies 4?, Figs. 4 and 7, the plies being made of suitable fuel resistant, substantially inelastic or unstretchable flexible material, preferably a strong woven fabric impregnated and coated on both sides with synthetic rubber. While two plies are shown each for the upper and lower portions of the diaphragm, it is to be understood one ply or more than two plies may be used for each of these portions. Between the upper and lower plies is mounted a filler or padding, preferably a readily resiliently distortable member, such as the tubular ring as of synthetic rubber. The surface of such a material will not readily rub or slip against the surfaces of the contacting diaphragm plies. Ring 39 is located in the free zone or region between where the plies are coirpressed against each other by casing members H and I2 and by plates !6 and I1. As in the usual pumps, this free region is of substantially less radial extent than the diameter of plates IE and IT. The overall area of cross section of ring relatively to the extent of the plies, is such that it will have a snug fit between them when diaphragm i3 is in its neutral position as shown in Fig. 4. In this position, the fit is such that there is no slack in the plies, a certain amount of tension in them preferably being present. As the diaphragm is moved from its neutral position, ring as is forced to assume a substantially elliptical shape, Figs. 5 and 6, by the compressive force exerted by plies 4,6 and 4'! as the tension in them is increased. This is due to the fact that as the diaphragm moves away from its neutral position, the free space available between the upper plies 46 and the lower plies 4! becomes less, to allow for an increase in the extent of the diaphragm as a whole. At the extreme upper and lower ends of the diaphragm stroke, as shown in Figs. 5 and 6 respectively, the minor axis of the ellipse formed by the ring is at a minimum, but not small enough preferably to allow the ring to become entirely collapsed. It will thus be seen that for all positions of the diaphragm, the plies will be fully extended without the presence of slack or sagging. This means that when the diaphragm I3 is moved up for its suction stroke, all elements of it radially inward from where its outer edge is gripped by casing members I I and i2, are simultaneously moved up. There is no lost motion. Similarly for the downward or feed stroke of the diaphragm, all its elements not gripped by said members, are simultaneously moved down without lost motion. Because of the elimination of lost motion from its strokes, my diaphragm is very efficient. This is true when the stroke has the full amplitude possible for it or when the amplitude is less, as when the carburetor resists the reception of fuel to such an extent as to prevent the full extension of spring 29. Wear of the pump parts also lessens the amplitude of the strokes. In the mass production of pumps, there is bound to be variation in the sizes of the parts and their relative positions in the finished product. It is important that a standard size dia phragm be suitable to fit these variations, especially where they require a standard diaphragm to suit an increase over the standard in the maximum amplitude of stroke. The greater the amplitude of stroke, the greater must be the extent of the diaphragm between its supporting edge. The construction of my diaphragm and padding is such that the diaphragm can be stretched in extent to suit this condition, the stretching being effected by an increase in the flattening of filler tube 39 and not by a streaching of the plies.

The diaphragms of the prior art, especially those used in fuel pumps, are composed of flexible sheets of substantially inelastic material made of one or more plies. Such a diaphragm, one of which is shown at 3 in Patent No. 1,742,770, must have sufiicient extent between its supported portions to permit it to be moved to its positions of maximum amplitude of stroke. In Fig. 1 of said patent, diaphragm 3 is at the maximum limit or amplitude of its upward stroke. When a diaphragm is then moved to its neutral position, there is more material in it than necessary for it to extend to its supported portions. The result is that the slack in the diaphragm sags or wrinkles when said diaphragm is in any position other than one corresponding to the maximum amplitude of stroke. Accordingly, when the diaphragm is reciprocated, every element is not moved upward for the entire time of the upward stroke or downward for the entire time of the downward stroke, because for a considerable period of this time some of the elements lag behind to form the slack and the wrinkles resulting therefrom. This is not the case with my diaphragm because in the preferred form, described above, the slack is eliminated for all positions of the diaphragm in the course of its stroke. In the modified forms of my diaphragm described hereinafter, where the filler or padding is not compressible or resilient, a certain amount of slack is present, but it is very small compared to the slack necessary in the diaphragms of the prior art.

The diaphragms of the prior art stretch after long use, thereby developing more slack even than necessary for their functioning. With my diaphragm, considering that such a padding as tube 39 is under initial compression when in the .4

neutral position shown in Fig. 4, stretching of the material of the plies after long use will not introduce slack.

When the amplitude of stroke is small, my

diaphragm is especially efficient as compared c with the diaphragms of the prior art. The greatest slack is present with the latter during the whole period of a stroke where the stroke is of small amplitude, resulting in much lost motion.

With the preferred form of my diaphragm no slack is present and hence no lost motion even for strokes of very small amplitude. In some of the modified forms, of my diaphragm described below, only a minimum of slack is present.

It will be readily understood, that with slack absent or nearly so, the plies of my diaphragm will :be subjected to a minimum of flexing during its reciprocation. As a corollary to this there will be a minimum of sliding of one pl over the other. As seen in Fig. '7, the marks X and Y represent points on the upper plies &5 which would coincide if such plies assumed a horizontal position. They would assume relative positions such as indicated at X, Y if the upper plies would be given the downward curvature shown for the lower plies 41. However, most of this inter-surface slippage is prevented by the action of the cushion or padding member 39 which maintains the curvature of the layers in a constant upward bulge for the upper layers and a constant downward bulge for the lower layers.

The more flexing and sliding of the plies required of a diaphragm, the quicker it will wear out. Because flexing and slippage are at a minimum with my diaphragm, it will outlast an equivalent diaphragm of the prior art where slack and its consequent flexing and slippage are essential to the functioning of the diaphragm.

The new diaphragm, because it requires less flexing, has better performance at low temperature than the diaphragms of the prior art. The resistance of the plies to flexing is increased at low temperatures because the ply fabric tends to become stiller.

Because my diaphragm has little or no flexing, especially during strokes of small amplitude, it is subject to little wear when the required intake of fuel at the carburetor is restricted. Under this condition, the strokes of the prior art diaphragm must have strokes of greater amplitude for the same rate of fuel delivery and the diaphragm is subject to its maximum flexing because the amplitude of the strokes occurs at the region of the greatest diaphragm slack.

A further advantage of my diaphragm due to its lack of slack, over those of the prior art is that surges of increased pressure are to a great extent prevented at high speeds of reciprocation. Such surges are objectionable because they induce increased wear of the carburetor valve. They occur with the diaphragms of the prior art because of their inherent slack. For example, with the old type diaphragm connected to stem I5, when the latter is urged downward :by spring 29, due to the presence of the slack, little resistance is developed by the inertia of the fuel to the downward motion of the diaphragm until it nears the lower limit of its stroke. Due to this unresisted urging of said spring, stem 15 is permitted to develop a high momentum which is suddenly checked by the pressure of the diaphragm against the fuel near the lower end of the stroke. The kinetic energy developed by the stem is thus suddenly given up to the fuel, causing a surge of pressure in the feed line between the pump and the carburetor. On the other hand with my diaphragm, which is taut throughout its stroke, there is no release of resistance to the pressure of spring 29 and the consequent sudden stoppage of the stem by the fuel.

Other forms of padding may be used than that shown in Fig. 4. The cushioning or padding ring it of Fig. 8 and the cushioning or padding ring 69 of Fig. 9, which are made of foam or sponge synthetic rubber or the like, can be made to serve a similar purpose as the tubular ring 3% of Fig. 4. In Fig. 8, cushioning or padding ring is not necessarily made of foam rubber, it may be made of solid synthetic rubber, notches 5! in its edges permitting its ready distortion when compressed between the plies of the diaphragm as the latter is reeiprocated. In Fig. 11, ring 52 is of similar material to ring 5*? of Fig. 10, but it is provided with a web 53 which extends far enough radially inward so that it would come between the plies where they are clamped'by plates 66 and El.

In Fig. 12, the plies are separated by a gas 55 such as air which will function as a padding very much like ring 39. Instead of air a liquid filler could be used. A comminuted or powder filler could be used, preferably a powder having a minimum of internal friction, such as talcum powder. Instead of having the ring 50 of readily flexible resilient material, as foam rubber, it might be made of a rigid material such as of wood, aluminum or phenolic resin, or of a lesser rigid material as of a solid synthetic rubber. A rigid filler, or one nearly so, must not be of greater volume than the space shown between the plies in Figs. 5 and 6. This means that when a diaphragm of inelastic plies assumes its neutral position, the position of Fig. 4, there is some slack in the plies, as the possible space between them is greater in Fig. 4 than it is in either of Figs. 5 and 6. Whatever slack there is, is much less than with the diaphragms of the prior art which is to the advantage of the new diaphragm. The slack present in the above noted modified forms of new diaphragm can be eliminated if plies of elastic material, such as of synthetic rubber or the like, be used. In the latter case, the filler is of a size to occupy the entire space possible between plies when the diaphragm is in neutral position. Now when it assumes the position of extreme amplitude, as in Figs. 5 and 6, the plies must stretch which, of course, if elastic material be used, can occur.

While reference in the specification and claims is made to a diaphragm for use in a pump, I wish it to be understood that the reference is to be considered as broad enough where consistent with the context to apply to other situations where a flexible diaphragm functions by having 7 its outer edge and central part given relative reciprocation.

I claim:

A pump diaphragm having two oppositely disposed portions, each portion consisting of one or more plies of flexible material, clamping means holding said portions at their outer edge part in fixed relationship to each other, other clamping means holding said portions at their central part in fixed relationship to each other, leaving a free annular region between said parts with the portions detached from each other in said region, and a readily flexible resilient tubular padding ring in said annular region bulging the portions apart at said region when said parts are clamped.

2. A pump diaphragm, adapted to be gripped at its outer edge part and at its central part leaving a free region between said parts, having two oppositely disposed portions, each portion consisting of one or more plies of flexible substantially inelastic material, clamping means holding said portions at their outer edge part in fixed relationship to each other, other clamping means holding said portions at their central part in fixed relationship to each other and a synthetic rubber padding member located between the portions in said free region, said member resiliently bulging the portions apart in said region when said parts are gripped.

3. For use in a pump, a casing, a diaphragm positioned in the casing and an operating means, said diaphragm having two oppositely disposed portions, each portion consisting of one or more plies of flexible material clamped in fixed relationship to each other at their outer edge by the casing and in fixed relationship to each other at their central part by said operating means, and a readily flexible resilient member located between said portions between said outer edge and central part, said member bulging the portions apart resulting in a space being left between them, said member being resiliently deformed to suit the change in shape of said space as the central part of the diaphragm is varied in position.

4. In a pump, a diaphragm having two oppositely disposed portions, each portion consisting of one or more plies of flexible substantially inelastic material, clamping means holding said portions at their outer edge part in fixed relationship to each other, other clamping means holding said portions at their central part in fixed relationship to each other, leaving a free annular region between said parts, said portions being free of each other in said free region, said central part being reciprocated during the functioning of the pump, and a readily flexible resilient an nular member located between said portions in said region bulging the portions apart to check the formation of slack in the plies for all positions assumable by said central part.

HOWARD C. PORTER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 356,997 Gil Feb. 1, 1887 360,651 Boluss Apr. 5, 1887 1,461,086 Fesler July 10, 1923 1,610,473 Reybold Dec. 14, 1926 1,738,786 McKinley Dec. 10, 1929 2,389,412 Carlton Nov. 20, 1945 

